// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_AUDIO_FIFO_H_
#define MEDIA_BASE_AUDIO_FIFO_H_

#include <memory>

#include "base/macros.h"
#include "media/base/audio_bus.h"
#include "media/base/media_export.h"

namespace media {

// First-in first-out container for AudioBus elements.
// The maximum number of audio frames in the FIFO is set at construction and
// can not be extended dynamically.  The allocated memory is utilized as a
// ring buffer.
// This class is thread-unsafe.
class MEDIA_EXPORT AudioFifo {
public:
    // Creates a new AudioFifo and allocates |channels| of length |frames|.
    AudioFifo(int channels, int frames);
    virtual ~AudioFifo();

    // Pushes all audio channel data from |source| to the FIFO.
    // Push() will crash if the allocated space is insufficient.
    void Push(const AudioBus* source);

    // Consumes |frames_to_consume| audio frames from the FIFO and copies
    // them to |destination| starting at position |start_frame|.
    // Consume() will crash if the FIFO does not contain |frames_to_consume|
    // frames or if there is insufficient space in |destination| to store the
    // frames.
    void Consume(AudioBus* destination, int start_frame, int frames_to_consume);

    // Empties the FIFO without deallocating any memory.
    void Clear();

    // Number of actual audio frames in the FIFO.
    int frames() const;

    int max_frames() const { return max_frames_; }

private:
    // The actual FIFO is an audio bus implemented as a ring buffer.
    std::unique_ptr<AudioBus> audio_bus_;

    // Maximum number of elements the FIFO can contain.
    // This value is set by |frames| in the constructor.
    const int max_frames_;

    // Number of actual elements in the FIFO.
    int frames_pushed_;
    int frames_consumed_;

    // Current read position.
    int read_pos_;

    // Current write position.
    int write_pos_;

    DISALLOW_COPY_AND_ASSIGN(AudioFifo);
};

} // namespace media

#endif // MEDIA_BASE_AUDIO_FIFO_H_
